This disclosure concerns apparatuses and methods useful for sealing a perivalvular leak associated with an implanted heart valve. In particular, apparatus and methods are disclosed for percutaneously closing, and to promote healing of, an opening between the natural valve annulus and the wall of the implanted valve.
The human heart is a section of highly muscularized vasculature defining four chambers: the right atrium, the right ventricle, the left atrium, and the left ventricle. Each chamber is associated with a one-way valve for controlling the direction of blood flow. Blood flow is driven by pressure created by regular contraction (systole) and relaxation (diastole) of cardiac muscle. Contraction of the muscles surrounding the ventricles increases the pressure within the ventricular chamber driving blood through the one-way exit valve. When the chamber relaxes negative pressure is created which causes blood to flow in from the associated atria through the one-way entrance valve.
Deoxygenated blood is pulled into the heart via the right atrium, through the tricuspid valve, and into the right ventricle. During systole, ventricular pressure increases pushing deoxygenated blood out of the right atrium through the pulmonary valve. Blood is oxygenated in the pulmonary system and collects in the left ventricle. During diastole, oxygenated blood is pulled from the left atrium, through the mitral (or bicuspid) valve, and into the left ventricle. During systole, ventricular pressure increases pushing oxygenated blood out of the left ventricle through the aortic valve.
Each of the valves resist retrograde flow, for example, from the ventricles back to their corresponding atria or from the arteries back to their corresponding ventricles. Each valve is surrounded by an annulus comprising a dense fibrous ring which supports the valve. The collagenous ring of the annulus provides an anchor for the valve leaflets which must resist backflow pressure.
About 5 million Americans are diagnosed with heart valve disease every year. There are several types of heart valve disease, for example, valvular stenosis, and valvular insufficiency. Valvular stenosis occurs when the valve leaflets become stiff narrowing the valve opening and thus reducing the volume of blood that can pass through it. Valvular insufficiency occurs when the valve leaflets do not properly close allowing blood to flow retrograde across the valve.
It is well known to treat heart valve disease by replacing a diseased or damaged valve. The procedure, whether surgical or percutaneous, involves reshaping the annulus to receive a prosthetic heart valve (either bioprosthetic or mechanical). After implantation, perivalvular leaks can develop which allow backflow around the implanted valve between patient tissue and the implanted valve. These leaks can occur, for example, because the reshaped annulus does not conform to the shape of the implanted valve. Another cause may be an accumulation of calcium plaques on natural valve surfaces. When the annulus is expanded, in preparation for implantation, calcium deposits can fracture creating irregularities in the implantation site. Perivalvular leaks can result in diminished valve function, loss of blood pressure, increased stress on the heart, and hemolytic anemia. A need therefore exist for improved and/or alternate devices and systems for closure of perivalvular leaks.